Derivatives of pyridazone



United States Patent 6 Claims. (61. 71-25 The present invention relatesto new pyridazone derivatives. It also relates to a method ofcontrolling unwanted plant growth with these pyridazone derivatives.

It is an object of this invention to provide new and valuable pyridazonederivatives. Another object of the invention is the provision of amethod for controlling undesired plant growth, for example among cropplants, with the pyridazone derivatives without damaging the crop lants.p It is known thatl-phenyl-4-a-hydroxy-}3,B,[3-trichloroethylamino-5-chloropyridazone-(6)may be used as an active substance for herbicides (British patentspecification No. 929,457). .Its action is, however, unsatisfactory.

We have now found that pyridazone derivatives having the formula (inwhich R denotes a phenyl radical or a cycloaliphatic radical having sixto eight carbon atoms) have a good herbicidal action. Its effect is bothselective and total, and it is used in pre-emergence and post-emergencemethods. The active substances are suitable for destroying weeds amongcrop plants and for the complete destruction of plant growth for exampleat the edges of roads and on waste land.

Pyridazone derivatives to be used in accordance with this invention maybe prepared by conventional methods, for example by reaction of1-phenyl-4-amino-5-bromopyridazone-(o) with chloral, advantageously in asolvent, for example dimethylformamide.

The following may be given as examples of active substances:1-phenyl-4a-hydroxy-fi,[igB-trichloroethylamino- 5-bromopyridazone-(6):melting point 213 to 215 C., with decomposition; lcyclohexyl-4-a-hydroxy-B,;8,fi-trichloroethylamino-S-bromopyridazone-(6):melting point 215 to 220 C., with decomposition.

The plant growth regulants according to this invention may be applied assolutions,.emulsions, suspensions or dusts. The form in which they areapplied depends entirely on the purpose for which they are to be usedand should in all cases ensure a fine distribution of the activesubstance. The effect, particularly when using the regulants as totalherbicides, in premature drying out and in defoliation, may be furtherenhanced by the use of carrier substances which are themselvesphytotoxic, such as high boiling point mineral oil fractions orchlorohydrocarbons.

On the other hand selectivity with regard to growth inhibition issometimes more evident when using carrier substances which are inert toplants, for example in selective weedkilling in the cultivation ofonions or crop plants.

Mineral oil fractions having medium to high boiling points, for examplekerosene or diesel oil, and also coal tar oils and vegetable and animaloils, cyclic hydrocarbons, for example tetrahydronaphthalene andalky'lated naphthalenes, are suitable for the production of solutionscapable of being directly sprayed, these being added to the act-i-vesubstances according to this invention, with or without the use ofauxiliary solvents, for example xylene. Solutions in low boiling pointsolvents, such as alcohols, for example ethanol, isopropanol andmethylcyclohexanol; ketones, as for example acetone and cyclohexanone;ethers, as for example tetrahydrofurane and dioxane; hydrocarbons, forexample benzene, toluene, and xylene; aud also in chlorinatedhydrocarbons, such as chloroform, carbon tetrachloride,tetrachloroethane, ethylene chloride or trichloroethylene, are lesssuitable for direct application than for combination with suitableemulsifiers for the purpose of preparing concentrates for thepreparation of aqueous emulsions:

Aqueous formulations may be prepared from emulsion concentrates, pastesor wettable powders (sprayable powders) by adding Water. For thepreparation of the emulsions, the substances, as such or dissolved inone of the above-mentioned solvents, may be homogenized in Water bymeans of mixing agents or dispersing agents. The emulsifying anddispersing agents may be both cation-active emulsifying agents, such asquaternary ammonium compounds, and anion-active emulsifying agents, suchas soaps, soft soaps, aliphatic long chain sulfuric acid monoesters, andalso aliphatic-aromatic sulfonic acids, lignin sulfonic acids, longchain alkoxyacetic acids, but may also be nonionic emulsifying agents,for example polyethylene ethers of fatty alcohols and polyethylene oxidecondensation products. Concentrates may also be prepared from activesubstance, emulsifying or dispersing agent and if desired solvent, theseconcentrates being suitable for dilution With water. Compounds whichhave adequate basicity may be formed into salts with acids and used asaqueous solutions of salts.

Dusts may be prepared by mixing or common grinding of the activesubstance with a solid carrier material. Examples of carrier substancesare: talc, diatomaceous earth, kaolin, bentonite, calcium carbonate,boric acid, calcium phosphate, but also wood flour, cork dust, carbonand other materials. Scatterable granulates maybe obtained for exampleby using ammonium sulfate as the carrier material. Alternatively carriermaterials may be impregnated with solutions of the active substances inliquid solvents. Powder preparations or pastes which can be suspended inwater and used as sprays may be obtained by adding wetting agents andprotective colloids.

The various forms of application may be better adapted to the variouspurposes for which the active substances Example 1 Indian corn (Zeamays), barley (Hordeum vwlgare), Wheat (Triticum vulgare), beet (Betavulgaris), onions (Alium cepa), peas (Pisum sativum), wild mustard(Sinapis arvensis), white goosefoot (Chenopodium album), camomile(Matricaria chamomilla), sorrel (Rumex sp.), annual meadow grass (Poaannua), orchard grass (Dactylis glomerata) and slender foxtail (Alopecurus my0suroides) are shown in a greenhouse in plastic pots havinga diameter of8 vcm. and filled with loamy sandy soil andthen1-phenyl-4-(a-hydroxy-5,5,5-trichloroethyl) -amino-5- bromopyridazone-(6) (I), 1 cyclohexyl-4-(a-hydroxy- 5,5,5trichloroethyl)-amino-5-bromopyridazone-(6) (II) and, for comparison,1-phenyl-4-(a-hydroXy-5,5,5-trichloroethyl)-amino-5-chloropyridazone-(6) (III) are sprayed onto the surface of the soil in the plastic pots ata rate of application of 2 kg. of active substance per hectare dispersedin SOD-liters of water per hectare. Four weeks later, the followingresults are observed =no damage, 100=total destruction.

Example 2 The plants Indian corn (Zea mays), barley (Hordeum vulgare),wheat (T riticum vulgare), onions (Alz'um cepa), peas (Pisum sativum),wild mustard (Sinapis arvensis),white goosefoot (Chenopodium album),amaranth pigweed (Amaranthus retroflexus), camomile (Matricariach'amomilla), sorrel (Rumex sp.), annual meadow grass (Poa annua),orchard grass (Dactylis glomerata), and slender foxtail (Al pecurusmyosuroides) are sprayed at a growth height of to 18 cm. with compoundsI, II and III used in Example 1, the rate of application being in eachcase 2 kg. of active substance per hectare dispersed in 500 liters ofwater per hectare. Some days later it is observed that action sets inmuch more rapidly in the case of I and II as compared with III and afterthree weeks almost all of the weeds and weed grasses have withered. Theresults of the experi-' ment may be seen in the following table:

An agricultural cultivated area which has been sown with dicotyledonousweeds and weed grasses, for example wild mustard (Sinapis arvensis),white goosefoot (Chewater per hectare.

nopodium album), small nettle (Urtica urens), gallant soldier,(Galinsoga parviflora), cleavers (Galium apa- "rine), knotweed(Polygonum sp.), chickweed (Stella'ria media), annual rneadow grass (Poaannua), orchard grass (Dactylis glomerata) and slender foxtail,(Alopecurus myosuroides) is sprayed on the day of sowing with"compounds I and II used in Example I and, for comparison, with2-chloro-4,6-bis (ethylamino) s-triazine (IV) in each case at the rateof application of 5 kg. of,

active substance per hectare dispersed in 500 liters of and weedandgrasses from the start, while on the test area treated with the compoundIV the plants germinate.

Three to four weeks later, all the weeds and weed grasses1-cyclooctyl-4-(a hydroxyhave completely withered.5,5,5-trichloroethyl)-amino-5-bromopyridazone-(6) (V) has the samebiological activity as the compound I in Examples 3 and 4.

Example 4 Compounds .1 and Hand, for comparison, compound IV are sprayedat the rate of 5 kg. of active substance per hectare dispersed in 500liters of water per hectare to a Weed-infested cultivated area which isovergrown with wild mustard (Sinapis arvensis), white ,goosefoot(Chenopodium album), small nettle (Urtica urens), galperiodof threeweeks, the plants treated with compounds;

I, II and IV are completely withered.

Example5 In a greenhouse plastics pots having a diameter of 8 cm. arefilled with loamy sandy soil, and seeds of Zea mays (Indian corn),Hordeum vulgare (barley), Triticum vulgare (wheat), Beta vulgaris(beet), Pisum satz'vum (peas), Gorsypium sp. (cotton), Solanum tuberosum(potatoes), Sinapz's arvensis (wild mustard), Chenopodium album (whitegoosefoot) Matricaria chamomilla (camomile), Stellaria media(chickweed), Pod annua (annual meadow grass), Alapecurus myosuroides(slen- The soil thus prepared a is then treated with 2 kg. per hectareof compound V and, for comparison, with 2 kg. per hectare of compound IIII, each dispersed in 500 liters of water per hectare.

Four to five weeks later it can be observed thatthere is der foxt-ail)are sown therein.

a stronger herbicidal eifect'with compound V than with compound HI. Theherbicidal effect may be seen from the following table: I

Some time later it is observed that. the compounds I and Ilpreventgermination of the weeds,

0:n'o damage =t0tal destruction.

Exam pl e 6 [The plants Zea mays (Indian corn), Hordeum vulgare(barley), T riticum vulgare (wheat), Pisum sativum 5 (peas), Gossypiumsp. (cotton), Sinapis arvensis (wild mustard), Chenopodium album (whitegoosefoot), Amarantus retroflexus (amaranth pigweed), Matricariachamomilla (camomile), Stellaria media (chickweed), Poa annua (annualmeadow grass), Alopecurus myosuroides (slender foxtail) are treated in agreenhouse at a growth height of 3 to 15cm. with 2 kg. per hectare ofcompound V and, for comparison, with 2 kg. per hectare of compound III,dispersed in each case in 500 liters of water per hectare. Three to fourweeks later it is observed that there is a stronger action with compoundV than with compound HI. The herbicidal action may be seen from thefollowing table:

Active substance V III Crop plants:

Indian corn .10 10 10 10 2030 0 0 0 15-20 100 90 90-100 90 90 70-8090-100 90 80 40-50 Annual meadow grass- 80 50-60 Slender ioxtail 70-3050 0=no damage; 100=tota1 destruction.

6 We claim: 1. A pyridazone derivative having the formula in which Rdenotes a member selected from the group consisting of phenyl andcycloalkyl having six to eight carbon atoms.

2. 1-phenyl-4-(a-hydroxy-p,fi, 8 trichloroethyl)-amino-5-bromopyridazone-(6) 3. 1-cyclohexyl-4-(a-hydroxy 5,5,5trichloroethyl)- amino-S-bromopyridazone-(6).

4. 1-cyclooctyl-4-(a-hydroxy 5 8,18 trichloroethyl)-amino-S-bromopyridazone- 6) 5. A method for controlling unwantedvegetation which comprises treating the vegetation with a phytotoxicamount of a pyridazone derivative as claimed in claim 1.

6. A method for controlling unwanted vegetation which comprises treatingthe soil with a phytotoxic amount of pyridazone derivative as claimed inclaim 1.

No references cited.

NICHOLAS S. RIZZO, Primary Examiner.

1. A PYRIDAZONE DERIVATIVE HAVING THE FORMULA
 5. A METHOD FORCONTROLLING UNWANTED VEGETATION WHICH COMPRISES TREATING THE VEGETATIONWITH A PHYTOTOXIC AMOUNT OF A PYRIDAZONE DERIVATIVE AS CLAIMED IN CLAIM1.